The present invention pertains to edible shortening products such as margarine, which have a reduced trans-fatty acid content.
Edible shortenings were proposed many years ago as substitutes for natural products such as lard and butter. These shortenings may have a consistency ranging from creamy to hard and butter-like. Large quantities of such shortenings are sold for use in baking and as a substitute for butter. In order to be economical, edible shortenings are made from naturally occurring vegetable oils. By partially hydrogenating vegetable oils to a semi-solid or solid product, a range of xe2x80x9chardnessxe2x80x9d may be produced. Alternatively, non-hydrogenated vegetable oils may be blended with more fully hydrogenated, solid oils. Shortening intended as a butter substitute is a soft solid at room temperature, behavior termed xe2x80x9cplasticxe2x80x9d by those skilled in the art. Consumers easily discern relatively minor differences between butter and margarine, with respect to their consistency when cold and when warm, their spreadability, etc.
Hydrogenation of vegetable oils causes isomeration of non-hydrogenated cis-double bonds of unsaturated vegetable oil into their trans form. For example, oleic acid residues in triglycerides are converted into elaidic acid. Recently, trans-fatty acids have been implicated in raising the risk of heart disease by adversely affecting blood lipid levels.
The substitution of fat mimetics such as polyol fatty acid polyesters for partially hydrogenated oils has not proven totally successful. First, such mimetics frequently cause bowel discomfort. Second, the different structure of the mimetics causes difficulties in formulating shortening and margarine products which perform acceptably, and which will pass consumer scrutiny. These shortcomings are attested to in U.S. Pat. No. 5,194,281, where very specific combinations of fatty acids are employed in esterifying sucrose to form polyol fatty acid polyesters in order to produce acceptable products, and in U.S. Pat. No. 5,306,516, wherein complex formulations are necessary to prepare a product containing polyester fat mimetics.
It would be desirable to provide a substitute for all or part of the xe2x80x9chardxe2x80x9d hydrogenated vegetable oil fraction of semi-solid to plastic shortening and thus lower the trans-fatty acid content of the shortening, while maintaining the desirable baking characteristics and consumer-desired consistency. It would further be desirable to offer a margarine-like product with the spreadability and other physical and organoleptic characteristics of butter, and to produce a range of products in terms of hardness, etc.
It has now been unexpectedly discovered that up to 100% of hydrogenated vegetable oils in shortening formulations may be replaced by esterified propoxylated glycerine (xe2x80x9cEPGxe2x80x9d). The products thus obtained have properties acceptable to the consumer. The replacement of the xe2x80x9chard fractionxe2x80x9d of partially hydrogenated oil allows significant reduction of the trans-fatty acid content in vegetable oil-based shortening products.
By the term xe2x80x9cshorteningxe2x80x9d as used herein is meant an edible mixture of solid and liquid fats and fat mimetics, a substantial portion of the liquid fat being derived from natural sources such as corn oil, soybean oil, palm kernel oil, coconut oil, canola oil, cotton seed oil, etc. The xe2x80x9cshorteningsxe2x80x9d are edible, any may take the form of fluffy, low density, air and water-containing soft products of the consistency of whipped butter or margarine; semi-solid xe2x80x9cgreasyxe2x80x9d products having higher density but little or no air or moisture, such as are used for butter or lard substitution in baking or for frying; or products with the consistency of margarine or butter, having considerable water content but little air content, and ranging in consistency from soft and spreadable at room temperature or below, e.g., xe2x80x9csoftxe2x80x9d margarine, to solid and crumbly at room temperature, often exhibiting a xe2x80x9cfracturexe2x80x9d upon spreading as is observed with butter. In other words, the edible shortenings of the present invention may take all the forms and physical, chemical, and organoleptic characteristics of butter, lard, and their vegetable oil-based replacement products now commonly available in the marketplace.
By the term xe2x80x9cfat contentxe2x80x9d is meant the total, in weight percent based on total shortening weight, of the fat constituents, including fat mimetics, of the shortening product. In margarines, for example, total fat is usually about 80% by weight of the product weight, the remaining 20% being mostly water, but also including, where necessary, emulsifiers, antioxidants, anti-spatter agents, coloring agents, flavorants, sugar, salt, proteins; odorants, nutraceuticals such as stanol fatty acid esters and/or sterol fatty acid esters, etc. Other ingredients are well known to one skilled in the art of shortening formulation. Oily antioxidants such as xcex1-tocopherol and xcex1-tocopherol acetate are not considered as part of the fat content of the shortening product.
By the term xe2x80x9cpartially hydrogenated vegetable oilxe2x80x9d is meant a partially hydrogenated vegetable oil containing trans-unsaturated fatty acids. Such semisolid and solid products typically have iodine numbers above 10 and below the iodine number of the vegetable oil from which they are derived, typically below 60 and more typically in the range of 15 to 50. The greater the degree of hydrogenation, the lower the iodine number. Iodine number may be measured conventionally, i.e., by the xe2x80x9cWijs methodxe2x80x9d set forth in AOCS Official Method Col. 1-25.
By the term xe2x80x9chardstockxe2x80x9d is meant a fully hydrogenated vegetable oil characterized by a low iodine value, and hence substantially no remaining unsaturation. Iodine values lower than 10, and in particular about 2 or less are typical. Hardstock contains few trans-unsaturated fatty acids since there is very little if any unsaturation remaining.
By xe2x80x9cEPGxe2x80x9d is meant esterified propoxylated glycerine. Such products have the chemical structure 
where R is 
wherein R2 and R3 are individually selected from the group consisting of hydrogen and methyl and one of R2 or R3 is methyl, and R1 is the hydrocarbon residue of a saturated or unsaturated carboxylic acid substantially free of trans-unsaturation. Thus, R1 is a saturated or unsaturated, preferably unsaturated, hydrocarbon radical having 7-23 carbon atoms, preferably 12-23 carbon atoms, and more preferably 14-23 carbon atoms. Each R1 may be individually selected, i.e., mixtures of fatty acid residues may be found in the same molecule, or some molecules may have all one type of fatty acid residue while others have all another type of fatty acid residue. Most preferably, the fatty acids are obtained from natural sources, i.e., by hydrolysis of naturally occurring fats and oils, e.g., glycerine fatty esters. Sources include animal fat, vegetable oil, etc. Some of the 
groups may be replaced by hydrogen, i.e., the EPG may have less than three acyl groups on average. A minor portion of the acyl groups may have R1 which contain from 1 to 6 carbon atoms.
The degree of alkoxylation is defined as the sum of a, b, and c, where a, b, and c individually are integers from 0 to 20. In general, a, b, and c need not be equal. It has been found, for example, that when oxypropylating glycerine, a 3:1 propylene oxide/glycerine ratio (stoichiometric) will result in oxypropylation (xe2x80x9coxypropylationxe2x80x9d and xe2x80x9cpropoxylationxe2x80x9d are used synonymously) of approximately 63% of the available glycerine hydroxyl groups. Thus, the majority of molecules will have one free hydroxyl group. By employing larger amounts of propylene oxide, the number of free hydroxyls decreases. At a 4:1 propylene oxide/glycerine ratio, 82% of the hydroxyl groups are propoxylated, and at 5:1, propoxylation is complete. Preferably, the degree of propoxylation is minimally 2, more preferably at least 2.2, and most preferably in the range of 3 to 8. If the degree of propoxylation is 2.2 or more, the products will be edible but only partially digestible. For example as compared to olive oil, only 18% of the fatty acids of lower propoxylated (n=2.2) products will be liberated by pancreatic lipase. At degrees of propoxylation between 5 and 8, substantially no fatty acids will be liberated under these conditions.
Although not shown in the EPG structural formula, a most minor portion, i.e., less than 20 mol percent of the oxypropylene groups may be replaced by oxyethylene groups (e.g. both R2 and R3 are H). For simplicity of language, these oxyethylene group-containing alkoxylated glycerine species are also within the scope of the terms xe2x80x9cEPGxe2x80x9d and xe2x80x9cesterified propoxylated glycerinexe2x80x9d unless indicated to the contrary. The presence of oxyethylene groups changes the hydrophile/lipophile balance of the molecule, and may be present in all or part of the total EPG to adjust emulsion stability. In a similar vein, up to about 33% of the oxypropylene groups may be replaced by other oxyalkylene groups having greater hydrophobicity, i.e., 1,2-butylene oxide and 2,3-butylene oxide. The term xe2x80x9cpropoxylatedxe2x80x9d as used herein includes oxyalkylation with mixtures containing propylene oxide and minor portions, i.e., less than 50% by weight, of other alkylene oxides.
Following propoxylation, the propoxylated glycerine is esterified by conventional methods. Transesterification of propoxylated glycerine with fatty acid triglycerides may also be used. Suitable methods are disclosed, for example, in U.S. Pat. Nos. 4,983,329, 5,175,323, and 5,986,117, which are incorporated herein by reference. Catalyst removal is accomplished by standard techniques, when necessary, or may be neutralized.
A typical vegetable oil margarine is produced by forming a homogenous mixture of vegetable oil, partially hydrogenated vegetable oil and/or hardstock at elevated temperature, along with the desired amounts of water, emulsifiers, flavorants, and other additives. Typically, total fat content is about 80%. The liquid mixture is cooled rapidly with thorough agitation to form the desired, solid product. Large crystals, which tend to make the product grainy, are avoided. The actual degree of smoothness may be varied by altering the cooling rate or the rate of agitation or both. Changes in the solid/liquid fat ratio, water content, and emulsifier content may also affect the smoothness/graininess characteristics. Incorporation of air during this stage or at a later stage results in a less dense and generally softer product. Baking shortening is prepared similarly, but generally with lesser amounts of water, preferably substantially no water.
In a typical margarine formulation, the total fat will be comprised of about 50 parts vegetable oil and about 50 parts partially hydrogenated vegetable oil per 100 parts total fat. It has now been unexpectedly discovered that margarine and butter substitutes may be produced by substituting EPG for a portion, preferably at least 50% of the partially hydrogenated vegetable oil. Up to 100% preferably more than 20%, more preferably more than 30%, yet more preferably greater than 50%, and most preferably 60-90% of the partially hydrogenated vegetable oil is substituted by EPG. Hardstock may be retained in such formulations if desired, as hardstock contains substantially no trans unsaturated fatty acids. The substitution of EPG for all or a major amount of the partially hydrogenated vegetable oil also allows for a greater proportion of less expensive liquid vegetable oil to be used. Surprisingly, despite the totally different chemical structure due to the presence of oxyalkylene and polyoxyalkylene ether-linked moieties, the EPG of the present invention have been found to be compatible with vegetable oil and hydrogenated vegetable oil. Even more surprisingly, substitution of a portion of the partially hydrogenated vegetable oil content has allowed a product with a butter-like consistency to be produced. Preparation of products with butter-like consistency has been very problematic in the past, and minor differences tend to be noticed by consumers.
Typical margarine and/or shortening ingredients other than those essential to these products (fats and oils, water) are well known. In general, the formulations contain relatively low amounts of emulsifiers and compatibilizers, e.g., lecithin and Dimodan Emulsifier, oil based vitamins, e.g. vitamin A and xcex2-carotene, and both oil soluble and water soluble flavorants. The aqueous phase may be partially composed of milk or may contain milk solids, and generally contains salt and preservative, e.g. sodium ascorbate or sodium benzoate. The oil phase ingredients and water phase ingredients are typically blended separately, then mixed together with cooling to form the product. With water-free products such as frying oils or shortenings, the additional water phase ingredients are generally omitted, but antioxidants and flavorings may still be added. Oil soluble antioxidants such as BHT are preferred in such cases.
The products may also contain nutraceuticals or pharmaceuticals, for example ingredients believed to lower cholesterol or be otherwise beneficial, such as the fatty acid esters of phytosterols or plant sterols, e.g., stanol or sterol fatty acid esters. The composition may also contain esters of xcfx89-3 and xcfx89-6 fatty acids, and other products believed to be xe2x80x9chealth smart.xe2x80x9d
Edible shortening compositions were prepared using conventional equipment. The fatty shortening ingredients were heated and stirred to a liquid, homogenous composition. The liquid composition was cooled with agitation in a portable Armfield votator. Past experience has shown a positive correlation between laboratory results using the Armfield votator and larger, pilot plant quantities. The control, Comparative Example C-1, contained no EPG, but instead was derived from soybean oil (L-soy) and partially hydrogenated soybean oil (H-soy). The formulations tested are presented in Table 1. The EPG is a 5 mol propoxylate of glycerin, esterified with fatty acids derived from rapeseed, soya, and/or canola oils.